Theisen, Stefan Quantum Gravity & Unified Theories, AEI-Golm, MPI for Gravitational Physics, Max Planck Society;
379526.pdf (Verlagsversion), 2MB
Lüst, D., Theisen, S., & Zoupanos, G. (1988). Four-dimensional heterotic strings and conformal field theory. Nuclear Physics B, 296(4), 800-836. doi:10.1016/0550-3213(88)90399-9.